1. Field of the Invention
The present invention relates to an industrial visual stethoscope system and an industrial visual stethoscope method, especially to an industrial visual stethoscope system and a method for distinguishing cracks caused by forging from scars caused by exterior impact.
2. Description of the Prior Arts
Nowadays, many appliances or components are made from cylindrical metal workpiece by various kinds of processing, such as forging, casting or turning. The workpiece may get heated due to high speed abrasion or other reason during the process, or the workpiece may even be directly under heat treatment. When the workpiece is cooled down, crystallites inside of the metal workpiece may be rearranged. With reference to FIG. 15, as this time, a crack A may be formed on an outer surface of the workpiece. The crack A may cause a great impact on a structural strength of the workpiece, and thus any workpiece will be under detection to find out the defective product having the crack A.
With reference to FIG. 16, however, the workpiece may get hit and then form scars B during the manufacturing or in transportation. The scars B may not affect the structural strength of the workpiece, and are ignorable. But it is hard to distinguishing the cracks A from the scars B with the naked eyes, and thus a specific detecting method is needed.
The most common detecting method is using fluorescent powder. When the workpiece is magnetized, the workpiece is covered by fluorescent powder and then rinsed with water to remove the fluorescent powder. The crack is relatively deep and narrow, while the scar is relatively shallow and wide, such that the fluorescent powder inside the cracks is hard to be washed away. Then, the workpiece is irradiated with a fluorescent lamp, and if there are recesses shining with fluorescent light, these recesses are cracks.
However, the aforementioned detecting method by using fluorescent powder has the following shortcomings. First, the fluorescent powder pollutes and damages the environment, and is also harmful to the human body. Second, the crack may be formed in an inner wall of the workpiece if the workpiece is a tube, and the conventional fluorescent detecting method is not applied to detect the inner wall of the tube.
To overcome the shortcomings, the present invention provides an industrial visual stethoscope system and an industrial visual stethoscope method to mitigate or obviate the aforementioned problems.